extrapyramidal system - parkinson's disease
DESCRIPTION
#Basic knowledge 1.Extrapyramidal system ( structure, function, interconnection) 2.Role of substantia nigra 3.Dopamine vs. Acetylcholine #Movement disorders – Parkinson’s disease 1.Facts about Parkinson’s disease 2.Aetiology 3.Pathophysiology 4.Clinical featuresTRANSCRIPT
Week 5
Extrapyramidal disorders
Presenter : Bayan Al-GhadeerCollege of Medicine – King Faisal University
Learning Objectives
o Basic knowledge• Extrapyramidal system
( structure, function, interconnection)• Role of substantia nigra• Dopamine vs. Acetylcholine
o Movement disorders – Parkinson’s disease• Facts about Parkinson’s disease • Aetiology • Pathophysiology • Clinical features
Introduction
The voluntary movements are controlled by:
• The Pyramidal System• The Extrapyramidal System
The Extrapyramidal System• Main structures
① Corpus striatum
② Subthalamic nuclei
① Substantia nigra
③ thalamus
Basal Ganglia: - Corpus striatum - Amygdaloid nucleus - Claustrum
• Associated structures
④ red nucleus
⑤ reticular formation
⑥ cerebellum
Anatomical organization
• Functions of extrapyramidal system
• selective activation of movements and suppression of others • Initiation of movements
• Setting rate and force of movements
• Coordinating movements
The interconnection between components of the extrapyramidal system and other parts of the brain
Corticostriatel fibers
G
Striatopallidal fibers pallidothalamic fibers
thalamocortical fibers
GABA
P
GABA
P
G
Direct Pathway Indirect Pathway
Corticostriatel fibers
Striatopallidal fibers pallidosubthalamic fibers Subthalamopallidal fibers
pallidothalamic fibers
thalamocortical fibers
G
GABA
P
GABA
P
G
GABA
P
G
excitatory
Inhibitory
How does it really work ?!
G
GABA
PGABA
P
Direct Pathway
excitatory
Inhibitory
Indirect Pathway
G
GABA
P
GABA
P
G
GABA
P
excitatory
Inhibitory
The role of substantia nigra
Consist of two parts:① Pars Compacta: has dopaminergic neurons
serves mainly as input to the basal ganglia circuit, supplying the striatum with dopamine.
② Pars reticulata: has GABAergic neurons serves mainly as output, conveying signals from basal ganglia to other brain structures.
The role of dopamine and acetylcholine
D1
nigrostriatel fibers
nigrostriatel fibers
D
G
D2D
Dopamine excitatory
Inhibitory
D1
nigrostriatel fibers
nigrostriatel fibers
DD2
D
Ach Ach
Ach D
normally
Acetylcholine excitatory
Inhibitory
Movement disorders
Localized neurological diseases Extrapyramidal disease
--> Parkinson’s disease
• Is a neurodegenerative brain disorder • Described by James Parkinson • Annual incidence: 20 per 100,000• Prevalence: 190 per 100,000• Age of onset: 50 years or more• 5% of cases are familial.
Facts about Parkinson’s disease
Aetiology • The cause of the disease is unknown.
Factors play a role
Mutations Environmental triggers 1-methyl-4-phenyl-1 2 3 6-tetrahydropyridine (MPTP)
Pathophysiology
In Parkinson DiseaseNormally
D1
nigrostriatel fibers
nigrostriatel fibers
DD2
D
Ach Achinhibition
GABA
P
GABA
P
excitation
excitatory
Inhibitory
D1
nigrostriatel fibers
nigrostriatel fibers
DD2
D
Ach Achinhibition excitation
GABA
P
GABA
P
G
GABA
P
excitatory
Inhibitory
Clinical features
Motor features
Non-motor features
Motor features
Motor symptoms (Typically asymmetr
ic )
Motor features
Rigidity
> increase muscle tone causing stiffness
> Onset and progression: one arm leg on the same side trunk other body side
> Type of rigidity in Parkinson’s disease # Lead pipe rigidity
# Cogwheel rigidity
Motor features
Rigidity
Cerebral cortex Thalamus
Reticular formation
❶ Reticular formation becomes overactive
❷ Increase muscle tone
❸ Increase resistance to movement
Motor features
Resting tremor
> It’s described as -pill rolling-
> Onset and progression: (develops early in the disease) unilaterally in the upper limb all four limbs
> involuntary rhythmic shaking movement of hands, feet, arms, legs during rest.
> Prominent in the distal portions of the extremities.
Motor features
Bradykinesia
> is slowness of movement and inability or difficulty to initiate or carry out movements despite the presence of adequate strength.
> produces: ① Facial bradykinesia (mask-like face)
② Losing arm swinging while walking
③ Truncal bradykinesia
> dopamine motor cortex activity bradykinesia
Motor features
Postural instability
> difficulty adjusting to postural change leads to poor balance and tendency to fall
Flexed (stooped) posture, more trouble with
walking, may need assistance or need a
wheelchair to get around.
> produces:
Motor features
Others
• Dysphagia (impaired ability to swallow).• Speech disorders.• Gait problems• Fatigue.
Motor features Non-motor features
Autonomic• frequent urination • constipation• impotence• seborrhoea
Cognitive• slowness of thinking• dementia• depression
Other:• Pain - Musculoskeletal pain - Pain associated with dystonia - pain result from tremor
• Sleeping disorders – REM sleep behavior disorders
Summary
o Pyramidal and the extrapyramidal systems both are functioningtogether to control the voluntary movements
o Extrapyramidal system consist of two pathways: direct ( excitatory) pathway and indirect (inhibitory) pathway.
o Parkinson’s disease is a neurodegenerative brain disorder that is characterized mainly by bradykinesia, rigidity and tremor
References • Neurology and Neurosurgery Illustrated, 5E (2010) • Clinical Neuroanatomy, Richard S. Snell, 7E • Fundamental of neurology • http://pathology.mc.duke.edu/neuropath/nawr/motor-systems.html• http://pegasus.cc.ucf.edu/~cwatts/spa3101/Neuro4.html• http://www.mayoclinic.org/diseases-conditions/parkinsons-disease/basics/causes/con-20028488• http://www.uptodate.com/contents/etiology-and-pathogenesis-of-parkinson-disease?source=outline_link&view=text&anchor=H2#H2
Thank you !
Any Questions ?